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Search Results for ' Whiteflies'

PAL Questions: 2 - Garden Tools:

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Keywords: Whiteflies, Insect pests--Identification, Insect pests--Control, Root weevils, Rhododendrons--Diseases and pests, Dahlia

PAL Question:

I have a line of Ward's ruby azaleas. The three weakest ones have a lot of tiny notches in the leaves. I seem to remember the notches from the root weevil as being larger than these. Are the tiny notches from something else?

I also noticed that some of my dahlias have splotched leaves and that when I disturb the leaves, white-looking insects fly off the leaves. These flies apparently have spread to tomatoes as well. Are these whitefly? Will they disappear after the winter or is there some control I should use to prevent them from taking over?

View Answer:

First you need to get an accurate diagnosis of your problems. If you are in King County, you can bring samples to a Master Gardener Clinic.

Oregon State University offers this information about root weevils and Rhododendron (which includes Azaleas). It describes using beneficial nematodes as a control.

According to Washington State University Cooperative Extension's publication, How to Identify Rhododendron and Azalea Problems (1984), root weevil damage to foliage is not usually a serious problem. You can check for weevils with a flashlight at night to confirm that they are the source of the notches you are seeing. There are some Neem oil-based products that may be helpful, but they must be used at the correct times of year. See WSU's HortSense page (search under Ornamentals, then scroll down to Rhododendron, and select "weevil").

As for the dahlias and tomatoes, it is important to determine exactly what the insects are before proceeding with treatment. If they are whiteflies, you can put yellow sticky traps around the plants to trap them. University of California, Davis's Integrated Pest Management site has other recommended control methods, including reflective mulch. You may not want to use insecticidal soap:
"Insecticides have only a limited effect on whiteflies. Most kill only those whiteflies that come in direct contact with them. For particularly troublesome situations, try insecticidal soap or an insecticidal oil such as neem oil or narrow-range oil. Because these products only kill whitefly nymphs that are directly sprayed, plants must be thoroughly covered with the spray solution. Be sure to cover undersides of all infested leaves; usually these are the lowest leaves and the most difficult to reach. Use soaps when plants are not drought-stressed and when temperatures are under 80 degrees F to prevent possible damage to plants. Avoid using other pesticides to control whiteflies; not only do most of them kill natural enemies, whiteflies quickly build up resistance to them, and most are not very effective in garden situations."

Season All Season
Date 2008-01-10
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Keywords: Whiteflies, Helleborus, Disease-resistant plants

PAL Question:

I have a white fly infestation on Helleborus. Is there any natural control (Rodale recommends tobacco tea) -- anything less labor intensive?

View Answer:

According to The Organic Gardener's Handbook of Natural Insect and Disease Control, edited by Barbara Ellis (Rodale Press, 1996), whitefly can be controlled in the following ways:
- Catch adults on yellow sticky traps.
- Vacuum adults from leaves.
- Attract parasitic wasps and predatory beetles.
- Spray with insecticidal soap, kinoprene (Enstar) or garlic oil.
- Last resort: spray with pyrethrin.

Season Summer
Date 2006-08-11
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June 24 2013 12:55:25